Did the "Marsupial Lion" Climb Trees?

Thylacoleo was one strange mammal. A close relative of living koalas, kangaroos, and wombats, the largest species of Thylacoleo were lion-sized carnivores that stalked the Australian continent between 2 million and 45 thousand years ago. Despite its popular nickname "marsupial lion", however, Thylacoleo was quite different from any feline predator. Even though its long forelimbs were tipped with retractable claws its skull more closely resembled that of a koala, with curved incisors set in front of a pair of cleaver-like shearing teeth. This resemblance caused some naturalists to believe that Thylacoleo was just another herbivore, but more recent studies have confirmed that it most certainly was a carnivore.

But what kind of predator was Thylacoleo? Some have proposed that it hunted down prey and then dragged it into the trees, as a leopard does, while others have argued that it was more lion-like in habit. The entire argument hinges upon whether Thylacoleo could climb trees or not, which in turn rests on our understanding of the predator's anatomy. The details of the skeleton of Thylacoleo, particularly its hands and feet, can provide paleontologists with clues as to what it was capable of. Unfortunately scientists have had to cope with an incomplete understanding of the hind feet of Thylacoleo for years, but a recent discovery from an Australian cave has brought new information to the discussion. As reported by paleontologists Roderick Wells, Peter Murray, and Steven Bourne in the latest issue of the Journal of Vertebrate Paleontology a complete hind foot of Thylacoleo has finally been found.

In June 2005 the owners of Henschke's Quarry in Naracoorte, Australia contacted scientist Steven Bourne about some fossils they had found in a cave on their property. When scientists began to excavate it they found, among other things, the incomplete-yet-articulated remains of several Thylacoleo carnifex, including parts of a tail and a complete hind foot. These fossils form the basis of the new study.

When put together the complete left hind foot of Thylacoleo is quite different from that of a cat. Cats are digitigrade, or they are standing up on their "tippy toes" all the time. The foot of Thylacoleo, though, is plantigrade, or like ours in that the metatarsal bones support part of the foot that touches the ground (to pick an example among carnivores, bears also have plantigrade feet). The feet also have a bit of a curve to them; in the restored foot the bones around the ankle articulation slant to the left while the metatarsal and toes slant to the right.

The core of the paper is the descriptive work the scientists carried out (which includes sentences such as "The second tarsal row includes the cuboid, navicular, and the endo-, meso-, ento-cuneiforms," which brings back memories of human anatomy class), but it is what the feet can tell us about the life of Thylacoleo that is most interesting. While the parts of the foot around the ankle were most similar to the same bones in wombats and phalangers (herbivorous relatives of Thylacoleo in the group Diprotodontia) the toes were well-suited to grasping and digging into pliable surfaces. The curvature of the foot and the retractable claws that tipped the toes of Thylacoleo would have helped it to grasp tree trunks or grab onto the torso of its prey, but what did it really do?

The restored left foot of Thylacoleo carnifex, shown as if it were grasping a tree trunk or the trunk of a prey animal. (From Wells et al, 2009)

The traits that made Thylacoleo a formidable killer may have also helped it in climbing (and vice versa). As the authors state, it appears that Thylacoleo had feet that certainly could have supported it and helped to push it up into trees, and these anatomical peculiarities would have also been useful in handling prey. Thylacoleo certainly could have climbed up into trees if it wanted to, and the authors promise that they have uncovered other new anatomical evidence that suggest that the marsupial predator did climb trees. I certainly look forward to reading more about this as-yet-unpublished evidence.

More like this

A restoration of the skull of Thylacoleo. From The Ancient Life History of the Earth.Without a doubt, the extinct marsupial predator Thylacoleo was one of the strangest carnivorous mammals ever to have evolved. This predator from ancient Australia did not have piercing canines but instead bit into…

The famous footage of "Benjamin," a Thylacine that died in captivity due to neglect on September 7, 1936. It was the last known living member of its species.Convergent evolution can be a tricky thing, and one of the most celebrated examples of it (at least among creationists) is the case of the…

If you were to ask someone walking along the street what a fossil is, they'd probably tell you that fossils are the bones of ancient creatures that have turned into stone (or something similar). This isn't wrong, prehistoric bones that have been replaced by minerals are certainly fossils, but bones…

The stench emanating from the putrefying mammoth carcass carried for miles.
Though kept out of the sun by the long shadows of the surrounding pine trees, the corpse reeked as the flesh, sinew, and bone of the mammoth's body were slowly parceled out into the ecosystem by scavengers. The woolly…

FYI, I posted this to After the Bar Closes - we are "debating" a creationist who claims that marsupial wolves (thylacines) and placental wolves are more similar than different. Not sure if you are aware of it or not, but you might get a kick (or a facepalm) out of it.

Those illustrations look amazing. Does anyone know who did them? Many years ago, I went on a dig to the Lake Eyre region with Rod Wells, and I seem to recall him saying that he did his own art. If this is his work, I'm very impressed.

Donate

ScienceBlogs is where scientists communicate directly with the public. We are part of Science 2.0, a science education nonprofit operating under Section 501(c)(3) of the Internal Revenue Code. Please make a tax-deductible donation if you value independent science communication, collaboration, participation, and open access.

You can also shop using Amazon Smile and though you pay nothing more we get a tiny something.

More by this author

Laelaps is back up and running at my author website, http://brianswitek.com. Go there for new posts and updates on where this blog will ultimately settle. - Brian
Update (09/14/10): After a few months of blogging on my own, I'm proud to say that Laelaps has made the jump over to the new WIRED…

Important Update: The time has come to close things up here. I will no longer be blogging for ScienceBlogs.com. I am not sure where Laelaps will end up - perhaps back on Wordpress, perhaps elsewhere - but you can be sure that I will keep on writing about saber-toothed cats, whales that walked,…

A normal giant gliding ant (left) and an infested ant (right). The red color of the gaster is not caused by a pigment, but thinning of the exoskeleton combined with the color of the nematode eggs. From Yanoviak et al, 2008.In one of my favorite episodes of the animated TV show Futurama, the chief…

"Worker Bee" by Motion City SoundtrackI have been writing here at ScienceBlogs.com for about two years and nine months now. Some of you have been reading my posts since I started here (thank you for sticking with me!), but readers come and go over time, and so I am jumping on board with the "Who…

More reads

"In the future, maybe quantum mechanics will teach us something equally chilling about exactly how we exist from moment to moment of what we like to think of as time." -Richard K. Morgan
It’s absolutely true that, in quantum mechanics, there are certain pairs of properties that we simply can’t measure simultaneously. Measure the position of an object really well, and its momentum becomes more…

In case you didn't know, reality is science fiction.
If you doubt me, read the news. Read, for example, this recent article in the New York Times about Carnegie Mellon's "Read the Web" program, in which a computer system called NELL (Never Ending Language Learner) is systematically reading the internet and analyzing sentences for semantic categories and facts, essentially teaching itself…

Blurring, chopping and blocking. Three online items this week all deal with some pretty dynamic phenomena.
The blurring is in our perceptions. It turns out that if you even think you have lost money in an experiment, your ability to distinguish between musical notes will be hampered. What’s the connection? Dr. Rony Paz has been showing that this tendency to lump sounds together is tied to fear.…